1. Field of the Invention
The present invention relates to material dispensing equipment, and more particularly, but not by way of limitation, to a control system for providing a steady state supply of a feed stock material to processing equipment.
2. Brief Description of the Prior Art
In processing equipment that performs a unit operation such as that of a punch press or a beverage dispenser requiring material or articles (such as beverage lids or the like fed as a line) to be fed to the equipment, it is desirable that the feed stock be available upon demand so that there are no disruptions of the feed stock. That is, the processing equipment's feed stock should be unrestricted, and to this end, various inventory control mechanisms are available to assure a continuing and constant feed rate of feed stock to such processing equipment. This becomes increasingly more important and demanding of the inventory control mechanism when the processing equipment must adjust to varying rams of feed stock demands.
For example, materials such as steel and aluminum are often most efficiently processed to punch presses and the like in the form of long, continuous webs or strips. Such material is often supplied in the form of coils, and an uncoiling apparatus is used to draw material from the coil for feeding it to the downstream processing equipment. Similarly, a feed stock of incremental articles, such as beverage container lids, is often fed to processing equipment as a continuous line of such articles, often passing like a flexible continuum through twists and turns. A feed stock accumulator is commonly positioned between the coil assembly and the processing equipment to store a sufficient amount of material so that a steady-state flow of material is available to the processing equipment.
Accumulators used with uncoilers are often designed to form a slack loop of material which serves to provide a readily available, tension free supply of the material for the processing equipment. Accumulators of many such designs have been used successfully for many years. Illustrative of such accumulators are: U.S. Pat. Nos. 3,177,749 issued to Best et al.; 4,770,366 issued to Hood et al; 3,888,400 issued Wiig; 4,489,872 issued to Bolton et al. For example, both U.S. Pat. Nos. 3,888,400 to Wiig and 4,489,872 to Bolton teach an accumulator in which a loop of feed stock is detected by optical sensors which detect the presence or absence of the loop as material is fed to the loop from a coil assembly or the like and as material is withdrawn from the loop by the processing equipment. In each case the material feed rate is increased if the loop is shortened beyond a predetermined limit and the material feed rate is decreased if the loop is increased beyond a predetermined limit. However, none of the known prior art is helpful in maintaining the loop within the confinements of preset minimum and maximum excursions of the loop for widely variable demands by the processing equipment.
There is a need for an inventory control system that permits the storage of a sufficient quantity of material for the steady state feeding of material to processing equipment so that continuous feed stock is available during varying feed demand, while at the same time preferably functioning in a non-contact manner. Such a control system would include a control system which is able to teach itself to deal with feed stock loop excursions as operating conditions are experienced.